FFmpeg Source Code Analysis 2: main function and transcode function (to 2)

Original post address: http://blog.csdn.net/austinblog/article/details/24804455

 

First, we can see from the main function that the key explanation has been annotated. This function is in the FFMPEG. c file. The Code is as follows:

 

Int main (INT argc, char ** argv) {int ret; int64_t Ti; // registers the cleaning callback function register_exit (ffmpeg_cleanup); setvbuf (stderr, null, _ ionbf, 0);/* Win32 runtime needs this */av_log_set_flags (av_log_skip_repeated); parse_loglevel (argc, argv, options); If (argc> 1 &&! Strcmp (argv [1], "-d") {run_as_daemon = 1; av_log_set_callback (log_callback_null); argc --; argv ++;} // register the avcodec_register_all () component (); # If config_avdevice avdevice_register_all (); # endif initialize (); av_register_all (); avformat_network_init (); show_banner (argc, argv, options); term_init (); /* parse options and open all input/output files * // parse parameters and open the input/output file ret = ffmpeg_parse_options (argc, Argv); If (Ret <0) exit_program (1); If (nb_output_files <= 0 & nb_input_files = 0) {show_usage (); av_log (null, av_log_warning, "Use-h to get full help or, even better, run 'man % s' \ n", program_name); exit_program (1 );} /* File Converter/Grab */If (nb_output_files <= 0) {av_log (null, av_log_fatal, "at least one output file must be specified \ n "); exit_program (1);} // If (nb_input_files = 0) {// av_log (null, av_log_fatal, "at least one input file must be specified \ n"); // exit_program (1 ); //} current_time = Ti = getutime (); // audio/video conversion function if (transcode () <0) exit_program (1); Ti = getutime ()-Ti; if (do_benchmark) {printf ("RunTime: utime = % 0.3fs \ n", Ti/1000000.0);} av_log (null, av_log_debug, "%" priu64 "frames successfully decoded, % "priu64" decoding errors \ n ", decode_error_stat [0], de Code_error_stat [1]); If (decode_error_stat [0] + decode_error_stat [1]) * max_error_rate <limit [1]) exit_program (69); exit_program (limit? 255: main_return_code); Return main_return_code ;}

 

Read the transcode function below:

 

Static int transcode (void) {int ret, I; avformatcontext * OS; outputstream * ost; inputstream * IST; int64_t timer_start; // initialize the encoder that opens all output streams, open the decoder of all input streams and write the file headers of all output files. It will be detailed later. Ret = transcode_init (); If (Ret <0) goto fail; If (stdin_interaction) {av_log (null, av_log_info, "press [Q] to stop, [?] For Help \ n ");} timer_start = av_gettime (); # If have_pthreads if (ret = init_input_threads () <0) goto fail; # endif // loop, it does not exit until the system signal is received. While (! Received_sigterm) {int64_t cur_time = av_gettime ();/* If 'q' pressed, exits */If (stdin_interaction) if (check_keyboard_interaction (cur_time) <0) break; /* Check if there's any stream where output is still needed */If (! Need_output () {av_log (null, av_log_verbose, "No more output streams to write to, finishing. \ n "); break;} // specific conversion work, which will be detailed later. Ret = transcode_step (); If (Ret <0) {If (ret = averror_eof | ret = averror (eagain) continue; av_log (null, av_log_error, "Error while filtering. \ n "); break;}/* dump report by using the output first video and audio streams */print_report (0, timer_start, cur_time);} # If have_pthreads free_input_threads (); # endif // After the file is processed, write the remaining data in the buffer to the output file. /* At the end of stream, We must flush the decoder buffers */for (I = 0; I <nb_input_streams; I ++) {ist = input_streams [I]; if (! Input_files [ist-> file_index]-> eof_reached & ist-> decoding_needed) {output_packet (IST, null) ;}} flush_encoders (); term_exit (); /* write the trailer if needed and close file * // write the end of the output file (some do not need ). For (I = 0; I <nb_output_files; I ++) {OS = output_files [I]-> CTX; av_write_trailer (OS );} /* dump report by using the first video and audio streams */print_report (1, timer_start, av_gettime (); // disable all encoders. /* Close Each encoder */for (I = 0; I <nb_output_streams; I ++) {Ost = output_streams [I]; If (Ost-> encoding_needed) {av_freep (& Ost-> St-> codec-> stats_in); avcodec_close (Ost-> St-> codec) ;}// close all decoders. /* Close each decoder */for (I = 0; I <nb_input_streams; I ++) {ist = input_streams [I]; If (IST-> decoding_needed) {avcodec_close (IST-> St-> codec); If (IST-> hwaccel_uninit) ist-> hwaccel_uninit (IST-> St-> codec);}/* finished! */Ret = 0; fail: # If have_pthreads free_input_threads (); # endif if (output_streams) {for (I = 0; I <nb_output_streams; I ++) {Ost = output_streams [I]; If (OST) {If (Ost-> stream_copy) av_freep (& Ost-> St-> codec-> extradata ); if (Ost-> logfile) {fclose (Ost-> logfile); Ost-> logfile = NULL;} av_freep (& Ost-> St-> codec-> subtitle_header ); av_freep (& Ost-> forced_kf_pts); av_freep (& Ost-> apad); av_dict_free (& Ost-> opts); av_dict_free (& Ost-> swr_opts ); av_dict_free (& Ost-> resample_opts) ;}}return ret ;}

 

FFmpeg Source Code Analysis 2: main function and transcode function (to 2)